Emulsions of aminofunctional silicones are widely used in hair care compositions to provide various aesthetic benefits. Various types of emulsions have been commercially developed to provide water based products of such aminofunctional silicone polymers for use as hair conditioning agents. One method to prepare aminofunctional silicone emulsions involves emulsion polymerization techniques, where siloxane monomers are first emulsified, and then subsequently polymerized to a high molecular weight. Alternatively, mechanical emulsions may be prepared from pre-formed aminofunctional silicones.
Reducing the presence of solvents, un-reacted siloxanes, catalyst residues, cyclic polymerization byproducts, and other impurities in silicone emulsions is an ongoing challenge in the art. The need to reduce such impurities may arise, among other reasons, when such impurities are incompatible with downstream applications (for example, medical, cosmetic, and personal care applications), where the presence of such impurities would reduce the stability of an emulsion, or where regulatory requirements require removal or reduction of their presence. In particular, there is an interest to reduce the presence of cyclosiloxanes, such as octamethylcyclotetrasiloxanes (D4) and decamethylcyclopentasiloxanes (D5), in emulsions of aminofunctional silicones. In many instances D4 and D5 may be present in the process to prepare the aminofunctional silicone emulsions, alternatively they may be produced from side reactions upon storing the emulsion.